1. Chemical Formulas
A compound is represented by giving its chemical formula, a notation that uses atomic symbols with numerical subscripts to convey the relative proportion of atoms of different elements in the substance.

2. Ratio of atoms in compound
Molecula
formula
Empirical
Ratio of atoms in compound
Carbon
dioxide
CO2
1 carbon atom : two oxygen atoms
formaldehyde
CH2O
1 carbon atom : two hydrogen atoms : oxygen atom
Acetic acid
C2H4O2
1 carbon atom : two hydrogen atoms : 1 oxygen atom
Empirical and molecular formulas tell us the combining ratio of the atoms in the compound, but show nothing about how the atoms are attached to each other.
There are other types of formula that will show the connectivity of atoms in a molecule.